Add stats-table counters to the disk cache so we can expose stats through...

net/disk_cache/backend_impl.cc

Index: net/disk_cache/backend_impl.cc
===================================================================
--- net/disk_cache/backend_impl.cc	(revision 74821)
+++ net/disk_cache/backend_impl.cc	(working copy)
@@ -9,6 +9,7 @@
 #include "base/message_loop.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
+#include "base/metrics/stats_counters.h"
 #include "base/rand_util.h"
 #include "base/string_util.h"
 #include "base/stringprintf.h"
@@ -698,6 +699,7 @@
 
   CACHE_UMA(AGE_MS, "OpenTime", GetSizeGroup(), start);
   stats_.OnEvent(Stats::OPEN_HIT);
+  SIMPLE_STATS_COUNTER("disk_cache.hit");
   return cache_entry;
 }
 
@@ -783,6 +785,7 @@
 
   CACHE_UMA(AGE_MS, "CreateTime", GetSizeGroup(), start);
   stats_.OnEvent(Stats::CREATE_HIT);
+  SIMPLE_STATS_COUNTER("disk_cache.miss");
   Trace("create entry hit ");
   return cache_entry.release();
 }